1. Field of the Invention
The present invention is directed in general to integrated circuit devices and methods for manufacturing same. In one aspect, the present invention relates to the fabrication of CMOS metal gate devices and non-volatile memory devices integrated on a single substrate or chip.
2. Description of the Related Art
Non-volatile memory devices, such as EEPROM and flash memory, are used in computers and other electronic devices to store data and/or programming instructions that can be electrically erased and reprogrammed and that must be saved when power is removed. Embedded non-volatile memory (NVM) has become increasingly important in applications ranging from data and code storage to circuit trimming and customization. By embedding a non-volatile memory in a CMOS device, a single chip device can be manufactured and configured for a variety of applications. While the introduction of novel gate stack materials for forming high-k metal gate stacks using gate last processes has improved device performance and reduced feature sizes for transistor devices, there are a number of integration options and challenges associated with the integration of such novel materials with existing polysilicon nanocrystal thin film storage bitcells. For example, as the dimensions of transistors decrease, the height of the conventional gate stacks used to form NVM bitcells has been reduced to prevent the “gate last” processing steps from damaging the NVM bitcell gates. In addition, the smaller device dimensions can create reliability concerns from shorting between select gate contacts and control gate contacts that are not sufficiently isolated from one another.
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the drawings have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for purposes of promoting and improving clarity and understanding. Further, where considered appropriate, reference numerals have been repeated among the drawings to represent corresponding or analogous elements.